RFR (S) 8183229: Implement WindowsSemaphore::trywait

[Mikael Gerdin]

Hi all,

To help with some upcoming patches I'd like to add the trywait operation 
to the platform-independent Semaphore class. It's currently lacking a 
Windows-implementation.

Testing: JPRT testing on Windows platforms
Webrev: http://cr.openjdk.java.net/~mgerdin/8183229/webrev.0/
Bug: https://bugs.openjdk.java.net/browse/JDK-8183229

Thanks
/Mikael